I have seen the future and it's Mexican. After a recent trip across the border I saw new Ford Transits everywhere as well as several other kinds of Euro vans I could not ID. I think if they can survive Mexican roads, drivers and conditions, they might be tougher than we think. I also saw quite a number of the VW version of the Sprinter that VW and Mercedes collaborated on. Doesn't look much different from the Sprinter, at least from the outside.
But on the topic of efficiency, there are two issues I see. Since we wont be getting the Euro diesel engines the mileage increase is relatively small but if you have a large fleet and can save 15% of your fuel costs I would say that's HUGE.
I suspect the real economy issue with these vans has more to do with the manufacturing efficiency for the car companies here than fuel economy. They are already designed and built so Ford USA doesn't have to do any thinking or make any additional investment in design and manufacture. Then it is cheaper and easier to make a unibody than a body on frame and they have several other advantages: they are more rigid, quieter, it is easier to design crumple zones and crash-resistance into them and they have much better external volume to internal volume ratio.
I think the notion that they are automatically going to be fragile and incapable of standing up to off-roading is not necessarily true. I don't know what the new Ford Transits are like off-road but these <